Magnetic tape cartridge

ABSTRACT

A magnetic tape cartridge includes an opening  1 C through which a magnetic tape is drawn out, and a slide door  6  that slides along a sidewall  1 D provided with the opening  1 C to open and close the opening  1 C. The opening  1 C is provided in part of the sidewall  1 D across a lower half  1 A and an upper half  1 B of the cartridge case  1.  At least one of a lower half portion and an upper half portion of the sidewall is provided with a holding groove  1 L that receives a front end portion  6 A of the slide door  6  when the opening is closed. Therefore, the upper half  1 B and the lower half  1 A of the magnetic tape cartridge may be smoothly combined.

BACKGROUND OF THE INVENTION

[0001] This invention relates to magnetic tape cartridges, and moreparticularly to a magnetic tape cartridge that permits easy mounting ofa slide door openably attached to an opening through which a magnetictape may be drawn out.

[0002] LTO (Linear Tape Open) standard-compliant magnetic tapecartridges have prevailed in the realm of the magnetic tape cartridgesused as an external recordable medium for data backup of a computer orthe like. The magnetic tape cartridge of this type includes a singlereel of magnetic tape and other components in a cartridge case comprisedof a lower half and an upper half. At a side of the cartridge case, anopening through which the magnetic tape is drawn out is formed acrossthe lower and upper halves. A slide door shaped like a thin plate foropening/closing the opening is slidably fitted in shallow guide groovesrespectively formed in the lower and upper halves and kept in such aposition as to close the opening under the stress of a spring member.

[0003] When the magnetic tape cartridge of this type is loaded in adrive that reads and writes data on the magnetic tape, a loadingmechanism in the drive opens the slide door of the opening, and a singlereel of magnetic tape is drawn out through the opening. The magnetictape that is drawn out, then, runs across a head of the drive; therebydata is recorded on or read out of the magnetic tape. When the magnetictape cartridge is unloaded from the drive, the slide door is moved bythe action of the spring member to the position in which the slide doormay close the opening in order to keep out dust.

[0004] In an assembly process of the above-described magnetic tapecartridge, a lower edge of the slide door is fitted in the shallow guidegroove of the lower half of the cartridge case under the stress of thespring member toward a direction in which the slide door is closed.Thereafter, the upper half is combined with the lower half, and thus anupper edge of the slide door is fitted in the shallow guide groove ofthe upper half, so that the slide door as well as the spring member ismounted in the cartridge case.

[0005] A description will be given more specifically of exemplifiedmounting operations of the slide door in the conventional magnetic tapecartridge as described above with reference to FIGS. 23A-C and 24.Referring now to FIG. 23A, there is shown, as one example of the aboveslide door, a slide door A3 shaped like a laterally-oblong thin platehaving upper and lower edges slidably fitted respectively into shallowguide grooves A2 of an upper half (not shown) and lower half A1 of thecartridge case. At a rear end (or side facing a direction in which theslide door A3 moves to open the opening) of the slide door A3 is formeda spring anchor portion A6 that anchors a distal end of a pressurizingspring arm A5 of a torsion coil spring A4 as the spring member. As shownin FIG. 23A, which is a magnified view of this example, the lower halfA1 includes a sidewall A8 in which an opening A7 is made. The torsioncoil spring A4 as the spring member, and the slide door A3 are fittedinto the guide groove A2 formed along an inside of the opening A7provided in the sidewall A8 of the lower half A1. In that event, theslide door A3 is mounted in the cartridge case in such a manner that theslide door A3 may be kept under the stress of the torsion coil spring A4toward a direction in which the slide door A3 moves to close theopening, and that a front edge A9 thereof is in contact with a contactportion A11 provided in a sidewall A10 of the lower half A1 of thecartridge case, as shown in FIG. 23B, which is a cross-sectional viewtaken along line X-X in FIG. 23A.

[0006] Turning to FIG. 24, in contrast, there is shown, as anotherexample of the above slide door, a slide door B4 shaped like alaterally-oblong thin plate having upper and lower edges slidably fittedrespectively into shallow guide grooves B2 of an upper half (not shown)and a lower half BI of the cartridge case. At a rear end (or side facinga direction in which the slide door B4 moves to open the opening) of theslide door B4 is provided a spring support rod B3 so as to project froma vertically middle position of the rear end toward rearward. At adistal end of the spring support rod B3 is formed a stopper head B5having a slot that may reduce a diameter of the head. A thin-helix longcompression coil spring B6 fitted in the spring support rod B3 of theslide door B4 with the diameter of the stopper head B5 at the distal endof the spring support rod B3 reduced is used for a spring member. Thediameter of the fitted stopper head B5 expands by the action of elasticrecovery, with the result that the compression coil spring B6 is securedso as not to come off; the compression coil spring B6 is wound aroundthe spring support rod B3 in a manner that permits compressivedeformation.

[0007] When the slide door B4 is fitted in the lower half B1 of thecartridge case as shown in FIG. 24, the slide door B4 is slightly tiltedso that the spring support rod B3 declinates a little, and the distalend of the spring support rod B3 including the stopper head B5 isbrought into contact with a support rod receiving groove B8 on a supportrod receiving block B7 provided on the lower half B1 of the cartridgecase, and is properly positioned. Next, the slide door B4 is slightlymoved in a direction to open the opening (to the left in FIG. 24) sothat the stopper head B5 may pass on a side of a spring receiving pieceB9 along the support rod receiving groove B8. Thereafter, the slide doorB4 is lowered toward the guide groove B2 in the lower half B1 while ahorizontal orientation of the slide door B4 is being restored, and thelower edge thereof is fitted into the guide groove B2.

[0008] The example as shown in FIGS. 23A through 23C keeps the slidedoor A3 open upside until an upper half (not shown) is combined with thelower half A1. Moreover, the guide groove A2 that receives the slidedoor A3 is shallow. Accordingly, the slide door A3 tends to fall in adirection perpendicular to a face of the slide door A3, particularly, ina direction indicated by an arrow YA inward of the cartridge case asshown in FIG. 23C that is a section taken along line Y-Y in FIG. 23A.Falling of the slide door would make the slide door A3 difficult toneatly fit into the guide groove A2 in the lower half A1 or the guidegroove in the upper half (not shown), in some instances.

[0009] On the other hand, the example as shown in FIG. 24 would have thespring support rod B3 deviated from a direction extending from thesupport rod receiving groove B8, or would have the spring support rod B3curved, when the distal end of the spring support rod B3 projected fromthe slide door B4 is brought into contact with the support rod receivinggroove B8 on the support rod receiving block B7 provided on the lowerhalf B1, and is positioned. Consequently, The stopper head B5 on thedistal end of the spring support rod B3 could not be properly positionedin the support rod receiving groove B8, so that the compression coilspring B6 wound around the spring support rod B3 would possibly fail tobe hooked on the spring receiving piece B9.

[0010] In short, during an assembly process of the conventional magnetictape cartridge, the slide door having a lower edge to be fitted in ashallow guide groove in a lower half of a cartridge case would likelyfall when the lower edge is fitted into the shallow guide groove in thelower half, and a stress of the spring member would possibly lift up theend of the slide door at a side facing a direction in which the slidedoor moves to open the opening, so as to get off the guide groove.Moreover, the compression coil spring wound around the spring supportrod of the slide door would fail to be securely hooked on the springreceiving piece. Therefore, when the slide door is mounted in thecartridge case while the lower half and upper half of the cartridge caseare combined during the assembly process of the conventional magnetictape cartridge, the lower edge of the slide door would not be neatlyfitted into the guide groove in the lower half, or the upper edge of theslide door would not be neatly fitted into the guide groove in the upperhalf; thereby failure in mounting the slide door would likely occur.This tendency would not be negligible when the slide door is mountedusing an assembly robot.

SUMMARY OF THE INVENTION

[0011] Therefore, it is a first exemplified object of the presentinvention to provide a magnetic tape cartridge that permits smoothcombination of an upper half and lower half of a cartridge case.Moreover, it is a second exemplified object of the present invention toprovide an assembly method of a magnetic tape cartridge in which a slidedoor may be securely mounted using an assembly robot. Further, it is athird exemplified object of the present invention to provide an assemblysupportive device that can securely guide a distal end of a springsupport rod for a slide door onto a support rod receiving block in alower half of a cartridge case, so that the assembly operation of theslide door using the assembly robot may be securely performed.

[0012] In order to achieve the above first object, an magnetic tapecartridge according to one exemplified aspect of the present inventioncomprises an opening through which a magnetic tape is drawn out, theopening being provided in part of a sidewall of a cartridge case acrossa lower half and an upper half of the cartridge case; and a slide doorthat slides along the sidewall provided with the opening to open andclose the opening. In this magnetic tape cartridge, at least one of alower half portion and an upper half portion of the sidewall is providedwith a holding concave portion that receives a front end portion of theslide door when the opening is closed.

[0013] When the magnetic tape cartridge according to the presentinvention is assembled, first, each component such as a reel and asafety lug is mounted respectively in a predetermined position of thelower half. Next, a spring member is mounted in the lower half, andthereafter the slide door is fitted into a guide groove in the lowerhalf formed along the inside of the sidewall provided with the opening.At this stage, the slide door is constantly stressed by the action ofthe spring member toward a direction in which the slide door moves toclose the opening, and the front end is kept in contact with an inneredge of the opening that is provided in the sidewall of the lower halfto draw out a magnetic tape. According to the magnetic tape cartridge inthis first aspect of the present invention, the sidewall includes theholding concave portion, and thus the front end of the slide door may beheld in the holding concave portion when the opening is closed with theslide door. Therefore, the slide door is supported with the holdingconcave portion and prevented from falling in a direction perpendicularto the face of the slide door. Further, disadvantageous circumstancesmay be avoided in which the slide door could not be neatly fitted intothe guide groove in the upper or lower half and thus the upper halfcould not be properly combined with the lower half.

[0014] In order to achieve the above second object, a method ofassembling a magnetic tape cartridge according to a second exemplifiedaspect of the present invention comprises the steps of: providing anopening through which a magnetic tape is drawn out in part of a sidewallof a cartridge case across a lower half and an upper half of thecartridge case; mounting a slide door that opens and closes the openingbetween guide portions each provided in the lower half and the upperhalf, while stressing the slide door with a spring member toward aposition in which the opening is closed. Further, in this methodaccording to the second aspect of the present invention, the mountingstep includes: mounting the slide door stressed with the spring membertoward the position in which the opening is closed by fitting a loweredge of the slide door into the guide portion of the lower half; keepinga mounting position of the slide door by holding an end of the slidedoor facing a direction in which the slide door moves to close theopening with a chuck device; and combining the upper half with the lowerhalf.

[0015] According to this method in the second aspect of the presentinvention, after the lower edge of the slide door is fitted into theguide portion of the lower half, the end of the slide door facing thedirection in which the slide door moves to close the opening is heldwith the chuck device to keep a position of the slide door, and thus theslide door may be kept upright without tilting or falling. Consequently,the lower edge and upper edge of the slide door may be securely fittedrespectively into each guide portion in the lower half and the upperhalf when the lower half and the upper half are combined.

[0016] In the above method of assembling a magnetic cartridge accordingto the second aspect of the present invention, the end of the slide doorfacing the direction in which the slide door moves to close the openingmay preferably be anchored with a stopper after the upper half iscombined with the lower half, and the stopper is removed from the slidedoor after the slide door is released from the chuck device. This allowsthe chuck device to be easily and smoothly detached from the front endof the slide door stressed toward the direction in which the slide doormoves to close the opening.

[0017] Moreover, in the above method, each guide portion provided in thelower half and the upper half may be comprised of not only a guidegroove, but also a rib provided between the slide door and upper andlower edges of the opening in the sidewall in such a manner as toslidably hold the slide door, or a plurality of projections, or thelike.

[0018] In order to achieve the above second object, a method ofassembling a magnetic tape cartridge according to a third exemplifiedaspect of the present invention comprises the steps of: providing anopening through which a magnetic tape is drawn out in part of a sidewallof a cartridge case across a lower half and an upper half of thecartridge case; mounting a slide door that opens and closes the openingbetween guide portions each provided in the lower half and the upperhalf, while stressing the slide door with a spring member toward aposition in which the opening is closed. In this method according to thethird aspect of the present invention, the above mounting step includes:mounting the slide door stressed with the spring member toward theposition in which the opening is closed by fitting a lower edge of theslide door into the guide portion of the lower half; holding the slidedoor by pressing an appropriate spot of an end of the slide door facinga direction in which the slide door moves to close the opening so thatthe end of the slide door facing the direction in which the slide doormoves to close the opening is prevented from rising out due to stressimposed by the spring member; and combining the upper half with thelower half.

[0019] According to this method in the third aspect of the presentinvention, after fitting the lower edge of the slide door into the guideportion of the lower half, the slide door is held by pressing anappropriate spot of the end of the slide door facing the direction inwhich the slide door moves to close the opening, and thus the slide doormay be kept upright without tilting or falling. Consequently, the loweredge and upper edge of the slide door may be securely fittedrespectively into each guide portion in the lower half and the upperhalf when the lower half and the upper half are combined.

[0020] In the above method of assembling a magnetic cartridge accordingto the third aspect of the present invention, the ‘appropriate spot’ forpressing the end of the slide door facing the direction in which theslide door moves to close the opening to hold the slide door is such aspot that may be pressed to effectively prevent the end of the slidedoor facing the direction in which the slide door moves to close theopening from rising out. The appropriate spot may be located above astraight line so extending as to join a contact point of one end of thespring member with the lower half and a contact point of the other endof the spring member with the slide door. Moreover, each guide portionprovided in the lower half and the upper half may be comprised of notonly a guide groove, but also a rib provided between the slide door andupper and lower edges of the opening in the sidewall in such a manner asto slidably hold the slide door, or a plurality of projections, or thelike.

[0021] Further, in order to achieve the above third object, according toa fourth exemplified aspect of the present invention, there is providedan assembly supportive device which guides a distal end of a springsupport rod onto a support rod receiving block provided on a lower halfof a cartridge case when a slide door for opening/closing an openingthrough which a magnetic tape of a magnetic tape cartridge is drawn outis fitted in the lower half of the cartridge case, a proximal end of thespring support rod being projected from the slide door, around whichspring support rod a compression coil spring is wound. The assemblysupportive device according to the fourth aspect of the presentinvention comprises: a guide member having a V-shaped groove thatreceives the distal end of the spring support rod; and a positioningdevice capable of moving the guide member from a retraction positionoutside the lower half to a use position over the support rod receivingblock on the lower half, and the guide member is formed with a slit soprovided as to cut through a bottom of the V-shaped groove partway fromone end.

[0022] According to this assembly supportive device in the fourth aspectof the present invention, the positioning device serves to move theguide member from the retraction position outside the lower half to theuse position over the support rod receiving block on the lower half, tolocate the guide member. In this operation, the slide door is held insuch a slightly tilted posture that the spring support rod of the slidedoor may orient obliquely in a gently declining direction. The distalend of the spring support rod is then pushed into a dead end (the otherend) of the V-shaped groove of the guide member, and moves back to theone end from which a slit is provided partway toward the other end.Through a series of these operations, the guide member guides the distalend of the spring support rod of the slide door through the slit formedat the bottom of the V-shaped groove onto the support rod receivingblock of the lower half.

[0023] Other objects and further features of the present invention willbecome readily apparent from the following description of preferredembodiments with reference to accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024]FIG. 1 is an exploded perspective view showing components of amagnetic tape cartridge according to a first embodiment of the presentinvention.

[0025]FIG. 2A is a partially magnified perspective view of a lower halfof a cartridge case, depicting a portion around the slide door as shownin FIG. 1.

[0026]FIG. 2B is a partially magnified perspective view of an upper halfof the cartridge case, depicting a portion around the slide door asshown in FIG. 1.

[0027]FIG. 3A is a diagram depicting a halfway stage of an operation ofmounting the slide door in the lower half of the magnetic tape cartridgeof the first embodiment.

[0028]FIG. 3B is a diagram depicting a final state of an operation ofmounting the slide door in the lower half of the magnetic tape cartridgeof the first embodiment.

[0029]FIG. 4 is a cross-sectional view taken along line Z-Z in FIG. 3Bfor illustrating a state in which a holding concave portion constitutingthe magnetic tape cartridge of the first embodiment accommodates a frontend portion of the slide door.

[0030]FIG. 5A is a cross-sectional view taken along line Z-Z in FIG. 3Bfor illustrating another exemplified embodiment of the holding concaveportion constituting the magnetic tape cartridge according to thepresent invention.

[0031]FIG. 5B is a cross-sectional view taken along line Z-Z in FIG. 3Bfor illustrating yet another exemplified embodiment of the holdingconcave portion constituting the magnetic tape cartridge according tothe present invention.

[0032]FIG. 6 is a perspective view for illustrating yet anotherexemplified embodiment of the holding concave portion constituting themagnetic tape cartridge according to the present invention.

[0033]FIG. 7 is an exploded perspective view showing components of amagnetic tape cartridge assembled according to a second embodiment ofthe present invention.

[0034]FIG. 8A is a perspective view showing a first operation processfor assembling the magnetic tape cartridge according to the secondembodiment of the present invention.

[0035]FIG. 8B is a plan view showing the first operation process forassembling the magnetic tape cartridge according to the secondembodiment of the present invention.

[0036]FIG. 9 is a perspective view showing a second operation processfor assembling the magnetic tape cartridge according to the secondembodiment of the present invention.

[0037]FIG. 10 is a perspective view showing a third operation processfor assembling the magnetic tape cartridge according to the secondembodiment of the present invention.

[0038]FIG. 11 is a perspective view showing a fourth operation processfor assembling the magnetic tape cartridge according to the secondembodiment of the present invention.

[0039]FIG. 12 is an exploded perspective view showing components of amagnetic tape cartridge assembled according to a third embodiment of thepresent invention.

[0040]FIG. 13 is a perspective view showing a first operation processfor assembling the magnetic tape cartridge according to the thirdembodiment of the present invention.

[0041]FIG. 14 is a perspective view showing a second operation processfor assembling the magnetic tape cartridge according to the thirdembodiment of the present invention.

[0042]FIG. 15 is a perspective view showing a third operation processfor assembling the magnetic tape cartridge according to the thirdembodiment of the present invention.

[0043]FIG. 16 is a perspective view showing a fourth operation processfor assembling the magnetic tape cartridge according to the thirdembodiment of the present invention.

[0044]FIG. 17 is a perspective view showing a whole structure of anassembly supportive device for a magnetic tape cartridge according to afourth embodiment of the present invention.

[0045]FIG. 18 is an enlarged perspective view of a guide member in theassembly supportive device as shown in FIG. 17.

[0046]FIG. 19 is a plan view for explaining an operation of the assemblysupportive device as shown in FIG. 17.

[0047]FIG. 20 is a side view for explaining an operation of the assemblysupportive device as shown in FIG. 17.

[0048]FIG. 21 is a diagram for illustrating a guide operation of theguide member in the assembly supportive device for the magnetic tapecartridge according to the fourth embodiment of the present invention,which guide member guides the spring support rod.

[0049]FIG. 22 is a diagram for illustrating a state of entry of thespring support rod as shown in FIG. 21 into a support rod guide groove.

[0050]FIG. 23A is a partially magnified perspective view of aconventional magnetic tape cartridge with a portion near an openingthereof described.

[0051]FIG. 23B is a cross-sectional view taken along line X-X in FIG.23A for explaining a state in which a lower half of the magnetic tapecartridge and a slide door are kept in contact with each other.

[0052]FIG. 23C is a cross-sectional view taken along line Y-Y in FIG.23A for explaining a state in which the slide door is falling.

[0053]FIG. 24 is a diagram of a spring support rod of a slide doorentering into a guide groove of the support rod during assemblyoperation of a conventional magnetic tape cartridge.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0054] A description will be given of the preferred embodiments of thepresent invention with reference to the drawings. First, referring toFIGS. 1 through 6, one exemplified embodiment of a magnetic tapecartridge according to the present invention will be described. Themagnetic tape cartridge is comprised of a lower half and an upper half,and an opening through which a magnetic tape is drawn out is provided ina sidewall portion of the cartridge case across the lower half and theupper half. At the sidewall of at least one of the lower half and theupper half is provided a holding concave portion that receives a frontend portion of a slide door when the opening is closed. In the drawings,FIG. 1 is an exploded view, in perspective, of components of themagnetic tape cartridge according to a first embodiment of the presentinvention, and FIGS. 2A and 2B are partially magnified perspective viewsof some components, each depicting a portion around the slide door asshown in FIG. 1.

[0055] The magnetic tape cartridge according to the first embodiment ofthe present invention is a so-called LTO standard-compliant model ofmagnetic tape cartridges. As shown in FIG. 1, this model of magnetictape cartridge typically includes a cartridge case 1 comprised of alower half 1A and an upper half 1B, and included inside the cartridgecase 1 are a single reel 2 around which magnetic tape MT is wound, alock plate 3 and a compression coil spring 4 for locking rotation of thereel 2, a slide door 6, a spring member 7, a safety lug 8, a cartridgememory chip (IC chip) 9, and the like.

[0056] In part of one sidewall 1D of the cartridge case 1 near a cornerof the cartridge case 1 is formed an opening 1C through which a magnetictape MT is drawn out such that the opening 1C spreads across the lowerhalf 1A and the upper half 1B. The opening 1C is configured to open andclose as the slide door 6 slides along the sidewall 1D of the lower half1A. The slide door 6 is configured to have a rear end thereof constantlystressed with a spring member 7 toward a position in which the openingis closed. The spring member 7 is a torsion coil spring having twocoiled portions 7A, 7A.

[0057] On the end of the magnetic tape MT is clamped a leader pin 10with a clip 11. The leader pin 10 may serve as a hook on which a tapeloading mechanism of a recording/reading device (not shown) catches theend of the magnetic tape MT to be drawn out through the opening 1C.

[0058] The lower half 1A and the upper half 1B each constitute a half ofthe cartridge case 1, and thus are combined into the cartridge case 1.In the lower half 1A, a plurality of stiffening ribs 1E, . . . areformed as appropriate in positions where the ribs do not interfere withthe reel 2, to provide a structure that permits each component to besupported and mounted by making use of these ribs 1E, . . . .

[0059] As shown in FIG. 2A, on an inside bottom surface 1F of the lowerhalf 1A, a shallow guide groove 1G having an approximately rectangularcross section extends along the one sidewall 1D in such a position as toadjoin a proximal bottom line of the sidewall 1D so that the slide door6 may slide smoothly. In the rib 1E that stands upright on the oppositeside of the guide groove 1G to the sidewall 1D, a spring hook portion 1Hwith which a fixable spring arm 7B at a rear end of the spring member 7is hooked up to the lower half 1A is formed in a vertical slit. Aholding portion 11 is engraved at the corner on the inner bottom surfaceof the lower half 1A to receive the leader pin 10 (see FIG. 1) when amagnetic tape is reeled up into the cartridge case 1.

[0060] The recording/reading device need pressurize the front end of theslide door 6 using an arm provided in the device in order to open theslide door 6; thus, a cutaway portion 1J through which the arm enters isprovided by cutting away two thirds or so from an upper end of a portionof the sidewall 1D with which the front edge 6A of the slide door 6 getsinto contact. Due to the cutaway portion 1J, a contact spot 1K withwhich the front end of the slide door 6 is brought into contact when theslide door has closed the opening 1C appears to rise from the bottomsurface 1F of the lower half 1A.

[0061] In the contact spot 1K, a receiving groove 1L havingapproximately rectangular cross section extends along the length of thecontact spot 1K so as to receive the front edge 6A of the slide door 6when the slide door 6 has closed the opening 1C.

[0062] Inside surfaces of the upper half 1B are, as shown in FIG. 2B,substantially symmetrical to the inside surfaces of the lower half 1A; aguide groove 1G that guides the upper edge of the slide door 6 is formedalong the sidewall 1D inside the opening IC, and a contact spot 1K withwhich the front edge (front end) 6A of the slide door 6 is brought intocontact when the slide door 6 has closed the opening 1C is provided inthe upper half 1B. In the contact spot 1K, as in the lower half 1A, areceiving groove 1L is provided so as to receive the front edge 6A ofthe slide door 6 when the slide door 6 has closed the opening 1C.

[0063] The spring member 7 is a torsion coil spring having two coiledportions 7A, 7A. When the spring member 7 is mounted in the lower half1A, the fixable spring arm 7B at the rear end is hooked up to the springhook portion 1H, and a pressure spring arm 7C at the front end is placedin the guide groove 1G; thereafter, the slide door 6 is fitted into theguide groove 1G while the pressure spring arm 7C is being pushed by therear end of the slide door 6 and kept bent.

[0064] The slide door 6 is, as shown in FIG. 2A, generally shaped like arectangular thin plate, and a rear end thereof is formed with a springhook portion 6B at which the pressure spring arm 7C may be hooked up, byrectangularly cutting out a midsection between top and bottom. A lowerend portion of the spring hook portion 6B is formed with a wedge portion6C that has bottom and end surfaces making an acute angle so as to scoopup the pressure spring arm 7C of the spring member 7 when the slide door6 is mounted in the lower half 1A with the spring member 7 being pushedand kept bent. In addition, An upper and rear end portion of the springhook portion 6B is cut off and formed with a protrusion 6D that juts outto the rear end of the slide door 6, so as to make the top thereof lowernot to interfere with the coiled portions 7A, 7A of the spring member 7when the slide door 6 is being opened.

[0065] When the thus-configured first embodiment of the magnetic tapecartridge is assembled, first mounted in the lower half 1A are amagnetic tape MT, a safety lug 8, a cartridge memory chip (IC chip) 9, acompression coil spring 4, and other parts. Next, as shown in FIG. 3A,the fixable spring arm 7B of the spring member 7 is hooked up at thespring hook portion 1H, and the pressure spring arm 7C is set into theguide groove 1G. The slide door 6 is then put inside the sidewall 1Daskew, and the wedge portion 6C is slid along the guide groove 1G towardthe pressure spring arm 7C as indicated by an arrow YB in FIG. 3A, toscoop up the pressure spring arm 7C. The pressure spring arm 7C is thenhooked up at the spring hook portion 6B, and the slide door 6 is fittedinto the guide groove 1G as shown in FIG. 3B.

[0066] The slide door 6 as thus fitted into the guide groove 1G isstressed by the action of the spring member 7 as shown in FIG. 1 towardthe direction in which the slide door 6 closes the opening 1C so as tokeep the opening closed. The slide door 6 tends to fall in a directionperpendicular to a face thereof, particularly toward the inside of thelower half 1A as indicated by an arrow YA in FIG. 4 before the upperhalf 1B and the lower half 1A are combined, because the guide groove 1Gis shallow.

[0067] However, according to the first embodiment of the magnetic tapecartridge, the contact spot 1K of the lower half 1A is provided with thereceiving groove 1L that receives the front edge 6A of the slide door 6when the slide door 6 has closed the opening 1C, and therefore the slidedoor 6 that has closed the opening 1C has the front edge 6A thereoffitted in the receiving groove 1L as shown in FIG. 4. This constructionmay prevent the slide door 6 mounted in the lower half 1A from fallingin the direction perpendicular to the face thereof. Accordingly, theslide door 6 would never fail to be neatly fitted into the guide groove1G of the upper half 1B or lower half 1A, and may be mounted smoothly.

[0068] The magnetic tape cartridge according to the present invention isnot limited to those having such a construction as in theabove-described first embodiment, but any changes may be made asappropriate without departing from the spirit and scope of the presentinvention. For example, in the first embodiment, the front edge 6A ofthe slide door 6 assumes a rectangular form in cross section, and thusthe receiving groove 1L provided at the sidewall 1D of the lower half 1Aassumedly has an approximately rectangular cross section. However, anyshapes that may receive the closed slide door 6 and support both facesat the front end of the slide door 6 to prevent the slide door 6 fromfalling in the direction perpendicular to the face thereof areapplicable to the receiving groove 1L, and the shape of the receivinggroove 1L may be modified according to the shape or the like of thefront edge 6A of the slide door 6, for example, into that having aU-shaped cross section as shown in FIG. 5A or a V-shaped cross sectionas shown in FIG. 5B.

[0069] Further, in the first embodiment, there is provided the receivinggroove 1L that extends vertically along a wall constituting the contactspot 1K of the lower half 1A. However, as shown in FIG. 6, a fittableprojection 6E that projects frontward from the front end of the slidedoor 6 and a fitted hole may be provided respectively on the edge of theslide door 6 and on the contact spot 1K of the lower half, so that thefittable projection 6E may be fitted into the fitted hole 1X when theslide door 6 has closed the opening 1C. This construction may also serveto prevent the slide door 6 provided in the lower half 1A from fallingbecause the fittable projection 6E is put into the fitted hole 1Xprovided in the contact spot 1K when the slide door 6 has closed theopening 1C. In this construction, the number, size, and shape of thefittable projection 6E and the fitted hole 1X provided respectively onthe slide door 6 and the lower half 1A may be arbitrarily determinedaccording to the size of the slide door 6 or the like.

[0070] In the above first embodiment, the lower half 1A and the upperhalf 1B each include the receiving groove 1L. However, if such anassembling process is adopted that the slide door 6 is mounted into thelower half 1A and thereafter the upper half 1B is combined with thelower half 1A to assemble the cartridge case 1, the receiving groove 1Lmay be provided only in the lower half 1A. Moreover, if such anassembling process is adopted for the cartridge case 1 that the slidedoor 6 is mounted into the upper half 1B and then combined with thelower half, the receiving groove 1L may be provided only in the upperhalf 1B.

[0071] Next, a description will be given of a method of assembling amagnetic tape cartridge as a second embodiment of the present invention,with reference to FIGS. 7 through 11. In this method, a lower edge of aslide door is fitted into a guide portion of a lower half of a cartridgecase, and thereafter an end of the slide door facing a direction inwhich the slide door moves to close an opening is held by a chuckdevice, so that the posture of the slide door may be kept appropriately.Among the referenced drawings, FIG. 7 is an exploded perspective viewshowing components of the magnetic tape cartridge assembled according tothe second embodiment of the present invention.

[0072] The method of assembling the magnetic tape cartridge according tothe second embodiment of the present invention is applied to an LTOstandard-compliant model of magnetic tape cartridges as shown in FIG. 1.The magnetic tape cartridge is, as shown in FIG. 7, comprised of acartridge case separated into a lower half 1A and an upper half 1B; inthe cartridge case are included a single reel 2 around which magnetictape MT is wound, a lock plate 3 and a compression coil spring 4 forlocking rotation of the reel 2, a release pad 5 for unlocking the reel2, a slide door 26 for opening and closing an opening 1C that isprovided in a sidewall of the cartridge case 1 to draw out the magnetictape, a torsion coil spring 27 as a spring member that stresses theslide door 26 toward a position in which the slide door 26 closes theopening IC, a safety lug 8, a cartridge memory chip (IC chip) 9, and thelike.

[0073] The above cartridge case 1 includes a substantially rectangularsidewall 1D in the lower half 1A and the upper half 1B respectively, andfor example in a right end portion of the sidewall 1D, the opening 1Cthrough which the magnetic tape is drawn out is formed across the lowerhalf 1C and the upper half 1B. On the bottom surface 1F of the lowerhalf 1A, near the inside of the sidewall 1D in which the opening 1C isformed, a shallow guide groove 1G in which the slide door 26 is slidablyfitted so that the guide groove 1G guides the slide door 26 is formed asa guide portion. The guide groove 1G is formed in a predetermined rangeincluding the opening 1C so that the slide door 26 may open and closethe opening 1C along the inside surface of the sidewall 1D. In the upperhalf 1B as well, a similar guide groove 1G is formed in a predeterminedrange including the opening 1C. In another sidewall 1D providedadjacently to the opening IC in the cartridge case 1, an operationopening 1N through which the slide door 26 is operated and opened isformed across the lower half 1A and the upper half 1B so that a stopperportion 1M for stopping the slide door 26 at a position where the slidedoor 26 closes the opening 1C is left in.

[0074] In the lower half 1A, a coupling rib 1P on the opposite side ofthe guide groove 1G to the sidewall 1D is formed with a spring hook slit1Q that hooks up a distal end of an arm portion 27A at one end of thetorsion coil spring 27, which distal end is bent so as to assume a shapeof letter L. The spring hook slit 1Q is formed downwardly to reach apredetermined depth from a top of the coupling rib 1P. A circularopening 1R is formed in a midsection of the bottom surface 1F of thelower half 1A; in the outside the circular opening 1R, arc ribs 1Ssurrounding the reel 2 are provided in contiguity with the side walls1D. Arc ribs are also formed in the upper half 1B, though not shown inthe drawing. The cartridge case 1 is formed with holding concaveportions 1T for holding the leader pin 10 that will be described laterin a position facing the opening 1C inside the slide door 36, atrespective positions in the upper half 1B and the lower half 1Acorresponding to upper and lower ends of the leader pin 10.

[0075] The reel 2 includes a cupped hub 2A of which an opening faces theupper half 1B in a midsection of the reel 2; on the bottom surface 2B ofthe cupped hub 2A, the release pad 5, lock plate 3, and compression coilspring 4 are mounted in this sequence. An external face of the bottomsurface 2B of the cupped hub 2A is exposed through the circular opening1R formed in the midsection of the bottom surface 1F of the lower half1A so that the reel 2 may be driven to rotate by a reel drivingmechanism in a driving device (not shown) into which the magnetic tapecartridge is loaded. On a distal end of the magnetic tape MT wound uparound the reel 2, the leader pin 10 to be drawn out with a hook of aloading mechanism in the driving device is fastened. The both ends ofthe leader pin 10 are held in the holding concave portion 1T in thecartridge case 1, so that the leader pin 10 is held in a position facingthe opening 1C inside the slide door 26.

[0076] The slide door 26 is shaped like a rectangular landscape thinplate with upper and lower edges slidably fitted into the guide grooves1G of the upper half 1B and the lower half 1A respectively. At a frontend of the slide door 26 facing a direction in which the slide door 26moves to close the opening 1C, an operation protrusion bar 26A operableto open the slide door 26 is formed. The operation protrusion bar 26A isprovided in a position facing an inside of an operation opening 1N ofthe cartridge case 1 so that the operation protrusion bar 26A may bepushed and moved by an operation arm (not shown) attached to the loadingmechanism in the driving device. At the rear end of the slide door 26facing a direction in which the slide door 26 moves to open the opening1C, a spring hook depression 26B to which an L-shaped distal end of thearm portion 27B at the other end of the torsion coil spring 27 is hookedup is formed. At a lower rear end surface of the slide door 26, that isa lower portion provided below the spring hook depression 26B, is formeda guide bevel 26C capable of scooping the L-shaped distal end of the armportion 27B to guide the same into the spring hook depression 26B. Thetorsion coil spring 27, as shown in FIG. 8A, includes two coiledportions 27C provided in series between the arm portion 27A at one endand the arm portion 27B at the other end to allow the torsion coilspring 27 a lot of latitude in a stroke of expansion. The two armportions 27A, 27B are configured to extend from the two coiled portions27C toward the same side in one plane with respect to a line containingproximal ends of the arm portions 27A, 27B. A distal end of the armportion 27A at one end is bent so as to assume a shape of letter L towhich a spring hook slit 1Q may be hooked up, while a distal end of thearm portion 27B at the other end is bent so as to assume a shape ofletter L that may be fitted into the guide groove 1G of the lower half1A and scooped by the guide bevel 26C of the slide door 26. It is to beunderstood that the torsion coil spring 27 may be configured to extendfrom the coiled portions 27C toward the opposite sides in one plane withrespect to a line containing proximal ends of the arm portions 27A, 27B.Further, the torsion coil spring 27 may be configured to have only onecoiled portion.

[0077] When the thus-configured magnetic tape cartridge is assembledaccording to the second embodiment of the present invention, the slidedoor 26 together with the torsion coil spring 27 is mounted into thecartridge case 1 by following a first operation step as shown in FIG. 8,a second operation step as shown in FIG. 9, a third operation step asshown in FIG. 10, and a fourth operation step as shown in FIG. 11. Adescription will be given of the method of assembling the slide door asthe second embodiment of the present invention step by step withreference made to FIGS. 7 through 10.

[0078] First, all internal components except the slide door 26 and thetorsion coil spring 27 are mounted each in a predetermined location inthe lower half 1A as shown in FIG. 7. The internal components include areel 2, a lock plate 3, a compression coil spring 4, a safety lug 8, acartridge memory chip 9, and the like. The assembly operation may beperformed manually, but a dedicated assembly device or a general-purposeassembly robot may be used, as well.

[0079] Next, as a first-half stage of the first operation step, as shownin FIG. 8A, a lower edge of the slide door 26 is fitted into the guidegroove 1G as a guide portion of the lower half 1A, while the slide door26 is being stressed by the torsion coil spring 27 as a spring membertoward a direction in which the slide door 26 moves to close the opening1C. In this assembly operation, first, the L-shaped distal end at oneend of the arm portion 27A is inserted into the spring hook slit 1Q ofthe coupling rib 1P and hooked up, and the L-shaped distal end at theother end of the arm portion 27B is inserted into the guide groove 1G.Subsequently, the lower edge of the slide door 26 is fitted into theguide groove 1G while the slide door 26 is located in a position inwhich the slide door 26 closes the opening 1C (to the right side in FIG.8). Thereafter, the slide door 26 is slid toward a direction in whichthe slide door 26 moves to open the opening 1C (to the left side in FIG.8). Accordingly, the L-shaped distal end of the arm portion 27B at theother end of the torsion coil spring 27 is scooped by the guide bevel 6Cprovided near the lower edge of the slide door 26, and fitted into thespring hook depression 26B. Thus, the lower edge of the slide door 26 isfitted into the guide groove 1G of the lower half 1A, while the slidedoor 26 is being stressed by the torsion coil spring 27 toward thedirection in which the slide door 26 moves to close the opening 1C. Theoperations as described above may be performed by a dedicated assemblydevice or an assembly robot.

[0080] Next, as a latter-half stage of the first operation step, asshown in FIGS. 8A, 8B, the front end of the slide door 26 facing thedirection in which the slide door 26 moves to close the opening 1C isheld with a chuck device CH so that an assembly position of the slidedoor 26 is kept. The chuck device CH as used herein may be controlled toadjust a position at least in X-Y directions (front-rear and right-leftdirections), and thus includes an immovable chuck piece CH1 and amovable chuck piece CH2 that may move toward or away from the immovablechuck piece CH 1. The immovable chuck piece CH2 may be driven, forexample, by an electromagnetic actuator. The chuck device CH asdescribed above holds the end of the slide door 26 facing the directionin which the slide door 26 moves to close the opening 1C between theimmovable chuck piece CH1 and the L-shaped movable chuck piece CH2extending across the operation protrusion bar 26A as shown in FIG. 8B,and thus keeps an upright posture of the slide door 26 without leaningor falling.

[0081] Following the first operation step, in the second operation step,the upper half 1B is combined with the lower half 1A, as shown in FIG.9. This operation may be performed manually or using a dedicatedassembly device or an assembly robot. At this stage, the slide door 26has its posture kept upright by the chuck device CH without leaning tothe left or right, or falling frontward or backward, and thus the upperedge of the slide door 26 may be securely fitted into the guide groove1G of the upper half 1B (see FIG. 7). Accordingly, even if a dedicatedassembly device or an assembly robot is used to combine the upper half1B with the lower half 1A, the assembly operation of the slide door 26may be securely carried out.

[0082] Thereafter, in the third operation step, while an front end faceof the slide door 26 facing the direction in which the slide door 26moves to close the opening 1C is stopped with a stopper rod S, the slidedoor 26 held by the chuck device is released, as shown in FIG. 10. Thestopper rod S may be selected among any components that may penetrateand retract through the opening 1C of the cartridge case 1 that isopenably closed by the slide door 26. The usable stopper rod S includesan operation rod for an electromagnetic actuator, and a rod membercoupled therewith, for example. The direction of penetration andretraction of the stopper rod S is not limited to a directionperpendicular to a plane containing the opening 1C, but may be anydirections oblique to the plane containing an open edge of the opening1C. When the stopper rod S penetrates into the opening 1C and stops thefront end of the slide door 26, the chuck device CH opens by separatingthe movable chuck piece CH2 from the immovable chuck piece CH1, andmoves a predetermined distance to the right as indicated by an arrow inFIG. 10, thereafter moving back to release the slide door 26.Accordingly, the chuck device CH may be smoothly detached from the frontend of the slide door 26 that is being stressed toward the direction inwhich the slide door 26 moves to close the opening 1C.

[0083] Subsequently, in the fourth operation step, the stopper rod S isretracted from the opening 1C to release the slide door 26, as shown inFIG. 11. Consequently, the slide door 26 slides toward the direction inwhich the slide door 26 may close the opening 1C by the action of thetorsion coil spring 27 as shown in FIG. 8; the front end of the slidedoor 26 is brought into contact with the upper and lower stopperportions 1M, 1M of the cartridge case 1, and is kept in a position wherethe slide door 26 closes the opening 1C. In this state, the operationprotrusion bar 26A of the slide door 26 faces the operation opening 1N(see FIGS. 9 and 10) between the upper and lower stopper portions 1M,1M, and is fitted into the operation opening 1N.

[0084] In the method of assembling the magnetic tape cartridge accordingto the second embodiment of the present invention, although the end ofthe slide door 26 facing the direction in which the slide door 26 movesto close the opening 1C is stopped using the stopper rod S after thelower half 1A and the upper half 1B are combined, the end of the slidedoor 26 facing the direction in which the slide door 26 moves to closethe opening IC may be stopped using the stopper rod S before the lowerhalf 1A and the upper half 1B are combined, if the end of the slide door26 facing the direction in which the slide door 26 moves to close theopening 1C has been held by the chuck device CH to keep a posture of theslide door 26.

[0085] Next, a description will be given of a method of assembling amagnetic tape cartridge according to a third embodiment of the presentinvention with reference to FIGS. 12 through 16. In this method, a loweredge of the slide door is fitted into a guide portion of the lower half,and thereafter an appropriated spot of the end of the slide door facinga direction in which the slide door moves to close the opening is pushedand held so that the end of the slide door facing a direction in whichthe slide door moves to open the opening is prevented from rising by thestress of the spring member. Among the referenced drawings, FIG. 12 isan exploded perspective view showing components of a magnetic tapecartridge assembled according to the third embodiment of the presentinvention.

[0086] The method of assembling the magnetic tape cartridge according tothe third embodiment of the present invention is applied to the LTOstandard-compliant model of magnetic tape cartridges as shown in FIG. 7.The magnetic tape cartridge is, as shown in FIG. 12, comprised of acartridge case separated into a lower half 1A and an upper half 1B; inthe cartridge case are included a single reel 2 around which magnetictape MT is wound, a lock plate 3 and a compression coil spring 4 forlocking rotation of the reel 2, a release pad 5 for unlocking the reel2, a slide door 36 for opening and closing an opening 1C provided in asidewall of the cartridge case 1 through which the magnetic tape isdrawn out, a torsion coil spring 37 as a spring member that stresses theslide door 36 toward a position in which the slide door 36 closes theopening 1C, a safety lug 8, a cartridge memory chip 9, and the like.

[0087] The above cartridge case 1 has a substantially square-shapedcontour as viewed from a top thereof, and includes four sidewalls 1D inthe lower half 1A and the upper half 1B respectively, and for example ina right end portion of one sidewall 1D among them, the opening 1Cthrough which the magnetic tape is drawn out is formed across the lowerhalf 1A and the upper half 1B. On the bottom surface 1F of the lowerhalf 1A, near the inside of the sidewall 1D in which the opening 1C isformed, a shallow guide groove 1G in which the slide door 36 is slidablyfitted so that the guide groove 1G guides the slide door 36 is formed asa guide portion. The guide groove 1G is formed in a predetermined rangeincluding the opening 1C so that the slide door 36 may open and closethe opening 1C along the inside surface of the sidewall 1D. In the upperhalf 1B as well, a similar guide groove 1G is formed in a predeterminedrange including the opening 1C. In another sidewall 1D providedadjacently to the opening 1C in the cartridge case 1, an operationopening 1N through which the slide door 36 is operated and opened isformed across the lower half 1A and the upper half 1B, while a stopperportion 1M for stopping the slide door 36 at a position where the slidedoor 36 closes the opening 1C is left in.

[0088] In the lower half 1A, at a side of the slide door 36 facing thedirection in which the slide door 36 guided by the guide groove 1G movesto open the opening 1C, a stopper piece 1U, a spring receiving block 1V,and a stem receiving block 1W are provided in contiguity with thesidewall 1D, as shown in FIG. 13, each spaced apart from each other andprojecting from the bottom surface 1F. The stopper piece 1U is projectedat an end position of the guide groove 1G, and brought into contact withthe end of the slide door 36 facing the direction in which the slidedoor 36 moves to open the opening 1C to stop the slide door 36 at aposition where the slide door 36 fully opens the opening 1C. On an upperedge of the spring receiving block 1V, a spring receiving groove 1V1that has a cross section shaped like an arc and receives one end of thecompression coil spring 37 is formed, and a spring receiving piece 1V2that blocks one end of the compression coil spring 37 is provided. Thespring receiving piece 1V2 is so provided upwardly from proximity of thespring receiving groove 1V1 as to slightly project into the springreceiving groove 1V1. Further, on the upper edge of the stem receivingblock 1W is formed with a stem receiving groove 1W1 that has a crosssection shaped like an arc to receive a spring support rod 36B that willbe described later (as shown in FIG. 12) of the slide door 36.

[0089] As shown in FIG. 12, a circular opening 1R is formed in a middlesection of the bottom portion 1F of the lower half 1A, and an arc-shapedrib 1S surrounding the reel 2 is provided in contiguity with thesidewall 1D outside the circular opening 1R. Though not illustrated, asimilar arc-shaped rib is formed in the upper half 1B. In the cartridgecase 1, a holding concave portion 1T for holding a leader pin 10 thatwill be described later in a position facing the opening 1C inside theslide door 36 is formed at each of the upper half 1B and the lower half1A as corresponding to the upper and lower ends of the leader pin 10.

[0090] The reel 2 includes a cupped hub 2A of which an opening faces theupper half 1B in a middle section of the reel 2; on the bottom surface2B of the cupped hub 2A, the release pad 5, lock plate 3, andcompression coil spring 4 are mounted in this sequence. An external faceof the bottom surface 2B of the cupped hub 2A is exposed through thecircular opening 1R formed in the midsection of the bottom surface 1F ofthe lower half 1A so that the reel 2 may be driven to rotate by a reeldriving mechanism in a driving device (not shown) into which themagnetic tape cartridge is loaded. On a distal end of the magnetic tapeMT wound up around the reel 2, the leader pin 10 to be drawn out by ahook of a loading mechanism in the driving device is fastened. The bothends of the leader pin 10 are held in the holding concave portion 1T inthe cartridge case 1, so that the leader pin 10 is held in a positionfacing the opening 1C inside the slide door 36.

[0091] The slide door 36 is shaped like a rectangular landscape thinplate with upper and lower edges slidably fitted into the guide grooves1G of the upper half 1B and the lower half 1A respectively. At a frontend of the slide door 36 facing a direction in which the slide door 36moves to close the opening 1C, an operation protrusion bar 36A operableto open the slide door 36 is formed. The operation protrusion bar 36A isprovided in a position facing an inside of an operation opening 1N ofthe cartridge case 1 so that the operation protrusion bar 36A may bepushed and moved by an operation arm (not shown) attached to the loadingmechanism in the driving device. In a vertically middle section of therear end of the slide door 36 facing a direction in which the slide door36 moves to open the opening 1C, a spring support rod 36B around whichthe compression coil spring 37 is wound is provided toward rearward. Ata distal end of the spring support rod 36B is formed a stopper head 36Chaving a slot that may reduce a diameter of the head so that the stopperhead 36C may be inserted into the compression coil spring 37.

[0092] The compression coil spring 37 is a thin-helix long coil spring,which is fitted on the spring support rod 36B of the slide door 36 withthe diameter of the stopper head 36C at the distal end of the springsupport rod 36B reduced. The diameter of the fitted stopper head 36Cexpands by the action of elastic recovery, with the result that thecompression coil spring 37 is secured so as not to come off; thecompression coil spring 37 is wound around the spring support rod 36B insuch a manner that permits compressive deformation.

[0093] When the thus-configured magnetic tape cartridge is assembledaccording to the third embodiment of the present invention, the slidedoor 36 together with the compression coil spring 37 is mounted into thecartridge case 1 by following a first operation step as shown in FIG.13, a second operation step as shown in FIG. 14, a third operation stepas shown in FIG. 15, and a fourth operation step as shown in FIG. 16. Adescription will be given of the method of assembling the slide door asthe third embodiment of the present invention step by step, withreference to FIGS. 12 through 16.

[0094] First, all internal components except the slide door 36 and thecompression coil spring 37 are mounted each in a predetermined locationin the lower half 1A as shown in FIG. 12. The internal componentsinclude a reel 2, a lock plate 3, a compression coil spring 4, a safetylug 8, a cartridge memory chip 9, and the like. The assembly operationmay be performed manually, but a dedicated assembly device or ageneral-purpose assembly robot may be used, as well.

[0095] Next, prior to the first operation step, the compression coilspring 37 is wound around the spring support rod 36B and secured so asnot to come off using the stopper head 36C. Thereafter, as the firstoperation step, as shown in FIG. 13, a lower edge of the slide door 36is fitted into the guide groove 1G as a guide portion of the lower half1A, while the slide door 36 is being stressed by the compression coilspring 37 as a spring member toward a direction in which the slide door36 moves to close the opening 1C.

[0096] In the first operation step, first, the slide door 36 is held insuch a slightly tilted posture that the spring support rod 36B mayorient obliquely in a gently declining direction. The stopper head 36Cat the distal end of the spring support rod 36B is then brought intocontact with the spring receiving groove 1V1 on the spring receivingblock 1V. Subsequently, the slide door 36 is slightly moved in adirection to open the opening 1C (to the left in FIG. 13) so that thestopper head 36 may pass on a side of the spring receiving piece 1V2along the spring receiving groove 1V1. Then, the slide door 36 islowered toward the guide groove 1G in the lower half 1A while an uprightorientation of the slide door 36 is being restored, and the lower edgethereof is fitted into the guide groove 1G. Thereafter, the slide door36 is slightly moved in a direction to close the opening 1C (to theright in FIG. 13) along the guide groove 1G, so that the front end ofthe slide door 36 is brought into contact with the stopper portion 1M inthe lower half 1A; consequently, the slide door 36 is released. Theabove operations are continuously performed manually, or using adedicated assembly device or an assembly robot.

[0097] Since one end of the compression coil spring 37 wound around thespring support rod 36B (see FIG. 12) is hooked up to the springreceiving piece 1V2 of the spring receiving block 1V, the slide door 36of which the lower edge is fitted in the guide groove 1G of the lowerhalf 1A in the first operation step is stressed toward the direction toclose the opening 1C (to the right in FIG. 13) by the action of thecompression coil spring 37, and a lower portion of the front end ispressed by the stopper portion 1M. Under these conditions, the stress ofthe compression coil spring 37 is directed substantially to a verticallymiddle spot of the slide door 36, and the spot or point of action ishigher than a position of the stopper portion 1M, so that the slide door36 gets tilted so as to allow the end facing the direction in which theslide door 36 moves to open the opening 1C (the left side in FIG. 13) torise slightly while the stopper portion 1M serves as a fulcrum. As aresult, the lower edge of the slide door 36 rises, at the end facing thedirection in which the slide door 36 moves to open the opening 1C, fromthe guide groove 1G.

[0098] Therefore, in the second operation step, as shown in FIG. 14, anappropriate spot at the front end of the slide door 36 facing thedirection in which the slide door 36 moves to close the opening 1C (atthe right side in FIG. 14) is pushed and anchored so as to prevent theend of the slide door 36 facing the direction in which the slide door 36moves to open the opening 1C (at the left side in FIG. 14) from risingby the stress of the compression coil spring 37. To be more specific, asshown in FIGS. 13 and 14, an upper portion of the operation protrusionbar 36A located in a higher position than the point of action of thestress of the compression coil spring 37 is pressed and anchored using astopper arm ST. The stopper arm ST is controlled to position so as to bemovable at least in directions in which the slide door 36 moves to openor close the opening 1C in such a position that a distal end of thestopper arm ST may translate and pass through the operation opening 1N(see FIG. 15) of the cartridge case 1.

[0099] Next, in the third operation step, as shown in FIG. 15, the upperhalf 1B is combined with the lower half 1A. This operation is performedmanually, or using a dedicated assembly device or an assembly robot.Since the slide door 36 is kept untilted in an upright posture using thestopper arm ST to prevent the end facing the direction in which theslide door 36 moves to open the opening 1C (at the left side in FIG. 13)from rising, the lower edge and the upper edge of the slide door 36 areproperly aligned with and securely fitted into the guide groove 1G inthe lower half 1A and the guide groove 1G in the upper half 1B (see FIG.12), respectively. Accordingly, in case where the upper half 1B iscombined with the lower half 1A using a dedicated assembly device or anassembly robot, the slide door 36 may also be securely mounted.

[0100] Thereafter, in the fourth operation step, as shown in FIG. 16,the stopper arm ST is moved toward a direction in which the slide door36 moves to close the opening 1C (to the right in FIG. 16) to get outthrough the operation opening 1N between the upper and lower stopperportions 1M, 1M of the cartridge case 1 (see FIG. 15). The slide door 36thereby slides toward the direction to close the opening 1C by theaction of the compression coil spring 37 (see FIG. 14); the front endthereof is brought into contact with the upper and lower stopperportions IM, IM of the cartridge case 1 and kept in a fully closingposition. In this situation, the operation protrusion bar 36A of theslide door 36 is aligned with and fitted into the operation opening 1Nbetween the upper and lower stopper portions 1M, 1M (see FIG. 15).

[0101] Subsequently, referring to FIGS. 17 through 22, a descriptionwill be given of an assembly supportive device for a magnetic tapecartridge according to a fourth embodiment of the present invention.Among the referenced drawings, FIG. 17 is a perspective view showing awhole structure of the assembly supportive device for a magnetic tapecartridge according to a fourth embodiment of the present invention. Theassembly supportive device for a magnetic tape cartridge is used, forexample, in assembling operations of the magnetic tape cartridge asshown in FIGS. 12 and 13 according to the third embodiment of thepresent invention. Thus, a detailed description of the magnetic tapecartridge assembled according to the above assembly operations will beomitted herein.

[0102] The assembly supportive device for a magnetic tape cartridgeaccording to the fourth embodiment of the present invention is, as shownin FIGS. 12 and 13, used to securely guide the stopper head 36C providedat a distal end of the spring support rod 36B of the slide door 36 intothe support rod receiving groove 1V1 on the support rod receiving block1V in the lower half 1A when the slide door 36 of the magnetic tapecartridge is fitted in the lower half 1A of the cartridge case 1.

[0103] As shown in FIG. 17, the assembly supportive rod 20 includes aguide member 21, a positioning device 22 capable of moving the guidemember 21 from a retraction position to a use position. The positioningdevice 22 includes a pivot arm 22A to which the guide member 21 isattached, a linear twist 22B that moves the pivot arm 22A vertically andpivotally.

[0104] The guide member 21, as shown in FIG. 18, includes a V-shapedgroove 21A having an opening upward, and a slit 21B so provided as tocut through a bottom of the V-shaped groove 21A partway from one endthereof. The width of the slit 21B is so designed as to allow the springsupport rod 36B of the slide door 36 around which the compression coilspring 37 is wound to pass through.

[0105] Next, a description will be given of an operation of fitting theslide door 36 into the lower half 1A shown in FIG. 12 using the assemblysupportive device 20 for a magnetic tape cartridge according to thefourth embodiment of the present invention. First, prior to theoperation of fitting the slide door 36, all internal components exceptthe slide door 36 and the compression coil spring 37 are mounted each ina predetermined location in the lower half 1A. The internal componentsinclude a reel 2, a lock plate 3, a compression coil spring (reelspring) 4, a safety lug 8, a cartridge memory chip 9, and the like. Thecompression coil spring 37 is wound up around the spring support rod 36Bof the slide door 36 in advance, and secured so as not to come off usingthe stopper head 36C. The assembly operation may be performed manually,but a dedicated assembly device (not shown) or a general-purposeassembly robot may be used, as well.

[0106] When the slide door 36 is mounted in the lower half 1A, theassembly supportive device 20 allows the pivot arm 22A of thepositioning device 22 to pivot so as to move the guide member 21 from aretraction position outside the lower half 1A indicated by solid linesto a position indicated by dash-double dot lines, as shown in FIG. 19.Next, as indicated by a solid line in FIG. 20, the pivot arm 22A islowered to move and position the guide member 21 to a use position overthe support rod receiving block 1V on the lower half 1A.

[0107] The slide door 36 is held in such a slightly tilted posture thatthe spring support rod 36B of the slide door 36 may orient obliquely ina gently declining direction, as shown in FIG. 21A. The distal end ofthe spring support rod 36B including the stopper head 36C is then pushedinto a back end (the other end) of the V-shaped groove 21A of the guidemember 21, and moves back to a front end (one end) from which a slit 21Bis provided partway toward the other end, as shown in FIG. 21B. Througha series of these operations, the guide member 21 guides the distal endof the spring support rod 36B of the slide door 36 to the bottom of theV-shaped groove 21A, as indicated by dash-double dot lines in FIG. 21C,and thereafter through the slit 21B onto the support rod receivinggroove 1V1 on the support rod receiving block 1V. The stopper head 36Cprovided on the distal end of the spring support rod 36B is moved alongthe support rod receiving groove 1V1 on the support rod receiving block1V toward the spring receiving piece 1V2.

[0108] In the present embodiment as described above, even if the springsupport rod 36B of the slide door 36 is slightly bent or incorrectlypositioned, and thus the stopper head 36C at the distal end thereof isnot properly aligned, the guide member 21 may securely guide the distalend of the spring support rod 36B including the stopper head 36C intothe support rod receiving groove 1V1 on the support rod receiving block1V in the lower half 1A, by using the V-shaped groove 21A. Accordingly,even if the series of operations as above are performed by an assemblyrobot, the distal end of the spring support rod 36B including thestopper head 36C in the slide door 36 may be securely guided into thesupport rod receiving groove 1V1 on the support rod receiving block 1Vin the lower half 1A.

[0109] Next, the positioning device 22 of the assembly supportive device20 pivots the pivot arm 22A, and moves the guide member 21 to theretraction position outside the lower half 1A. Subsequently, as shown inFIG. 22A, the spring support rod 36B of the slide door 36 is furthermoved along the support rod receiving groove 1V1 of the support rodreceiving block 1V toward the spring receiving piece 1V2, and, as shownin FIG. 22B, the stopper head 36C is allowed to pass on a side of thespring receiving piece 1V2. Then, as shown in FIG. 13, the slide door 36is lowered toward the guide groove 1G of the lower half 1A with aposture of the slide door 36 gradually restored to a horizontal andupright position, and the lower edge of the slide door 36 is fitted intothe guide groove 1G.

[0110] Thereafter, the slide door 36 is moved slightly along the guidegroove 1G toward a direction to close the opening 1C (to the right inFIG. 13), so that the front end thereof is brought into contact with thestopper portion 1M of the lower half 1A, and the slide door 36 isreleased. Lastly, the upper half 1B is combined with the lower half 1A.The above-described operations are continuously performed manually, orusing a dedicated assembly device or an assembly robot.

[0111] Although the preferred embodiments of the present invention havebeen described above, various modifications and changes may be made inthe present invention without departing from the spirit and scopethereof.

[0112] As described above, in the magnetic tape cartridge according tothe present invention, the slide door stressed by the action of thespring member so as to keep the opening through which magnetic tape isdrawn out closed has the front end thereof held in the holding concaveportion provided at the sidewall. Therefore, the slide door supported bythe holding concave portion is prevented from falling in a directionperpendicular to the face of the slide door. Consequently, the magnetictape cartridge according to the present invention may be smoothlyassembled.

What is claimed is:
 1. A magnetic tape cartridge comprising: an openingthrough which a magnetic tape is drawn out, the opening being providedin part of a sidewall of a cartridge case across a lower half and anupper half of the cartridge case; and a slide door that slides along thesidewall provided with the opening to open and close the opening,wherein at least one of a lower half portion and an upper half portionof the sidewall is provided with a holding concave portion that receivesa front end portion of the slide door when the opening is closed.
 2. Amethod of assembling a magnetic tape cartridge comprising the steps of:providing an opening through which a magnetic tape is drawn out in partof a sidewall of a cartridge case across a lower half and an upper halfof the cartridge case; mounting a slide door that opens and closes theopening between guide portions each provided in the lower half and theupper half, while stressing the slide door with a spring member toward aposition in which the opening is closed, wherein the mounting stepincludes: mounting the slide door stressed with the spring member towardthe position in which the opening is closed by fitting a lower edge ofthe slide door into the guide portion of the lower half; keeping amounting position of the slide door by holding an end of the slide doorfacing a direction in which the slide door moves to close the openingwith a chuck device; and combining the upper half with the lower half.3. A method of assembling a magnetic tape cartridge according to claim2, wherein the end of the slide door facing the direction in which theslide door moves to close the opening is anchored with a stopper afterthe upper half is combined with the lower half, and the stopper isremoved from the slide door after the slide door is released from thechuck device.
 4. A method of assembling a magnetic tape cartridgeaccording to claim 2, wherein each guide portion provided in the lowerhalf and the upper half is comprised of any one of a guide groove, a ribprovided between the slide door and upper and lower edges of the openingin the sidewall in such a manner as to slidably hold the slide door, anda plurality of projections.
 5. A method of assembling a magnetic tapecartridge comprising the steps of: providing an opening through which amagnetic tape is drawn out in part of a sidewall of a cartridge caseacross a lower half and an upper half of the cartridge case; mounting aslide door that opens and closes the opening between guide portions eachprovided in the lower half and the upper half, while stressing the slidedoor with a spring member toward a position in which the opening isclosed, wherein the mounting step includes: mounting the slide doorstressed with the spring member toward the position in which the openingis closed by fitting a lower edge of the slide door into the guideportion of the lower half; holding the slide door by pressing anappropriate spot of an end of the slide door facing a direction in whichthe slide door moves to close the opening so that the end of the slidedoor facing the direction in which the slide door moves to close theopening is prevented from rising out due to stress imposed by the springmember; and combining the upper half with the lower half.
 6. A method ofassembling a magnetic tape cartridge according to claim 5, wherein theappropriate spot for pressing the end of the slide door facing thedirection in which the slide door moves to close the opening to hold theslide door is located above a straight line so extending as to join acontact point of one end of the spring member with the lower half and acontact point of the other end of the spring member with the slide door.7. A method of assembling a magnetic tape cartridge according to claim5, wherein each guide portion provided in the lower half and the upperhalf is comprised of any one of a guide groove, a rib provided betweenthe slide door and upper and lower edges of the opening in the sidewallin such a manner as to slidably hold the slide door, and a plurality ofprojections.
 8. An assembly supportive device which guides a distal endof a spring support rod onto a support rod receiving block provided on alower half of a cartridge case when a slide door for opening/closing anopening through which a magnetic tape of a magnetic tape cartridge isdrawn out is fitted in the lower half of the cartridge case, a proximalend of the spring support rod being projected from the slide door,around which spring support rod a compression coil spring is wound, theassembly supportive device comprising: a guide member having a V-shapedgroove that receives the distal end of the spring support rod; and apositioning device capable of moving the guide member from a retractionposition outside the lower half to a use position over the support rodreceiving block on the lower half, wherein the guide member is formedwith a slit so provided as to cut through a bottom of the V-shapedgroove partway from one end.